The Collaborative International Dictionary of English v.0.48:

Prudish \Prud"ish\, a.
   Like a prude; very formal, precise, or reserved; affectedly
   severe in virtue; as, a prudish woman; prudish manners.
   [1913 Webster]

         A formal lecture, spoke with prudish face. --Garrick.
   [1913 Webster]

WordNet (r) 3.0 (2006):

prudish
    adj 1: exaggeratedly proper; "my straitlaced Aunt Anna doesn't
           approve of my miniskirts" [syn: priggish, prim,
           prissy, prudish, puritanical, square-toed,
           straitlaced, strait-laced, straightlaced,
           straight-laced, tight-laced, victorian]

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "prudish":
   Quakerish, Victorian, austere, censorious, choicy, choosy,
   conscientious, critical, decorous, demure, discriminating,
   discriminative, exacting, fastidious, formal, fussy, genteel,
   hidebound, meticulous, mid-Victorian, narrow, old-maidish,
   overmodest, particular, perfectionistic, picky, precise,
   precisianistic, priggish, prim, prissy, proper, punctilious,
   puristic, puritanic, puritanical, rigid, sanctimonious, scrupulous,
   selective, sensitive, severe, smug, squeamish, stern, stiff,
   stiff-necked, strait-laced, straitlaced, strict, stuffy